1. Field of the Invention
This invention lies in the field of polyester polyol compositions, and techniques for making the same.
2. Description of the Prior Art
Cellular polyurethane and polyisocyanurate polymers are well known to the art particularly for use in various types of thermal insulating applications. Such polymers are manufactured by reacting polyfunctional organic isocyanates with polyfunctional compounds containing free hydroxyl groups (e.g., polyols) in the presence of a blowing agent and (usually) a catalyst.
Because of the relative high cost of polyols useful in making cellular polymers, and because of property problems (such as friability, flammability, and blend compatibility, and the like), efforts have been made heretofore to find polyols adapted for chemical conversion into such cellular polymers which are as low cost as possible. Because of a tendency for lower cost polyols to produce product foams of less than desired properties, it has become commonplace to prepare and utilize blends of different polyols for reaction with organic polyisocyanates to produce product foams having desired combinations of properties. Through the use of carefully prepared and formulated resin precursor blends containing polyols which are then reacted with isocyanates, product foam problems can be avoided, such as lack of uniform core strength or core density, poor adhesion between foam core and adjacent substrate, excessive foam friability, and the like.
Aliphatic alcohol esters of phthalic acid are known (see Kessler et al. U.S. Pat. No. 1,714,173), and efforts have heretofore been made to employ at least one member of this class (diethylene glycol phthalate) as a polyol in the manufacture of cellular polymers; see, for example, the article by Reymore et al. entitled "Novel Isocyanurate Foams Containing No Flame Retardant Additives" in Journal of Cellular Plastics November/December 1978, pages 332-340.
It now appears that if phthalate polyester polyol compositions could be prepared and if such phthalic acid ester polyols could be prepared at low cost, then such compositions could and would have significant commerical value, particularly as additives to resin blends of the type adapted for reaction with organic isocyanates.